LED Tail Lites - Mounting Angle?

There are lots of LED lite assemblies out there, but I have not found anything about allowable mounting angle for effective viewing. From the displays at the shows it is very, very apparent that looking straight into a couple of dozen tail lamp assemblies flashing brake intensity is downright blinding in full daylight from across the room. If I were to mount a pair of say '50 Pontiac style lamps on the valance panel of a '33 that tilts back from vertical maybe 35 degrees are they going to be effective? I'm trying to keep from frenching in a round, vertical mounting surface into the panel if possible. Is there a mounting recommendation with these LED lites or one published anywhere?

I have seen them mounted at every possible angle on trailers, I think you could try it and see.